Conventional approaches for providing distinctive structural and aesthetic properties to liquid compositions include: the addition of specific structuring agents including both internal and external structuring agents. Examples of known internal structuring agents include: surfactants, electrolytes (which can promote the formation of worm like micellar self assembly structures). Known external structuring agents include polymers or gums, many of which are known to swell or expand when hydrated to form random dispersion of independent microgel particles. Examples of polymers and gums include: gellan gum, pectine, alginate, arabinogalactan, caageenan, xanthum gum, guar gum, rhamsan gum, furcellaran gum, carboxymethylcellulose and cellulose. See e.g. U.S. Pat. No. 6,258,771 to Hsu et al. U.S. Pat. No. 6,077,816 to Puvvada et al. U.S. Patent Publ. No. 2005/0203213 to Pommiers et al.; and WO 2006/116099 to Fleckenstein et al. Although gums have been used to provide structuring benefits, the gums are pH dependant, i.e. failing at pH above 10. Further, certain gums have been found to be susceptible to degradation in the presence of detersive enzymes. Thus, there remains a need for other external structuring agents less susceptible to these and other known problems.
Another composition reported to provide structuring benefits is cellulose, i.e. bacterial celluloses. Conventional uses of bacterial celluloses include improving rheological properties for hydraulic fracturing fluids used for hydraulic fracturing of geological formations; addition to well bore drilling muds; and as a food ingredient. See e.g. U.S. Pat. Nos. 5,350,528, 5,362,713, and 5,366,750. The bacterial cellulose is typically cultured using a bacterial strain of Acetobacter aceti var. xylinum and dried using spray drying or freeze drying techniques. Attempts to manufacture and prepare the dried bacterial cellulose compositions which can be rehydrated and activated into a bacterial cellulose network for use in end products are known. Examples of these attempts are provided in U.S. Pat. No. 6,967,027 to Heux et al. and U.S. Patent Publ. No. 2007/0027108 to Yang et al. See also U.S. Publ. Nos. 2008/0108714 to Swazey et al. and 2007/197779 to Yang et al. and WO Publication No. 2007/068344 to Cai et al.
Two structuring properties which are desired in liquid detergent compositions include bead and/or particle suspension capabilities and shear thinning capabilities. Although it has been reported that the addition of certain external structuring agents into liquid detergent compositions may provide certain shear thinning benefits, the ability to provide shear thinning capabilities alone is insufficient to determine whether the liquid detergent composition is capable of suspending bead particles over time. As such, there remains a need for an external structuring agent which provides both shear thinning benefits and bead suspension capabilities. Further, these structuring benefits are desired at as low a level of external structurant as possible for cost and formulation concerns. For example, excessive amounts of external structuring agent may provide the particle suspension capability but result in the liquid composition becoming overly viscous and non-pourable. Further, too much external structuring agent may also result in compositional opacity and cloudiness which can be undesirable.
As such, there remains a need for an external structuring agent which provides both shear thinning capabilities and sufficient particle suspension capabilities while avoiding one or more of the above mentioned problems encountered with conventional formulations.